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  1. MariaDB Server
  2. MDEV-5509

Seconds_behind_master incorrect in parallel replication

        Details

        • Type: Bug
        • Status: Closed
        • Priority: Major
        • Resolution: Fixed
        • Affects Version/s: 10.0.7
        • Fix Version/s: 10.0.9
        • Component/s: None
        • Labels:
          None

          Description

          As reported by plinux on #maria:

          09:03 < plinux> We found a display bug about parallel replication. When we update one row on master, and then stop
          the updates on master, we can found Seconds_Behind_Master is still increasing on slave

          I think the problem is a race between the SQL driver thread and the worker
          threads.

          Normally, the rli->last_master_timestamp is updated in stmt_done() to the
          timestamp of an event from the master. When next_event() reaches the end of
          the relay log, it is temporarily set to 0 to mark that SQL thread is caught
          up; SHOW SLAVE STATUS handles this value special.

          But with parallel replication, it can easily happen that the SQL driver thread
          reaches the end of the relay log before a worker thread calls stmt_done(),
          thus ending up with the wrong value in rli->last_master_timestamp and hence
          wrong output of SHOW SLAVE STATUS.

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                knielsen Kristian Nielsen added a comment - - edited

                Patch for review:
                http://lists.askmonty.org/pipermail/commits/2014-January/005802.html

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                knielsen Kristian Nielsen added a comment - - edited Patch for review: http://lists.askmonty.org/pipermail/commits/2014-January/005802.html
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                knielsen Kristian Nielsen added a comment -

                Fix pushed to 10.0-base and 10.0, will appear in 10.0.9.

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                knielsen Kristian Nielsen added a comment - Fix pushed to 10.0-base and 10.0, will appear in 10.0.9.

                  People

                  • Assignee:
                    knielsen Kristian Nielsen
                    Reporter:
                    knielsen Kristian Nielsen
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                    Dates

                    • Created:
                      Updated:
                      Resolved: